A. USB Wireless Engraver: These engraving tools can be charged via the USB interface. After a full charge, they can be used wirelessly for up to 30 minutes, helping you complete an engraving process. B. Visible Speed Adjustment: This metal engraving pen is equipped with a motor and has 3 speed settings ranging from 5000 to 25000 revolutions per minute to adapt to different situations. The lowest speed can be used for filing nails, while the highest speed can be used for metal engraving. C. Multiple Grinding Heads: These metal engraver kits include 30 rotary bits, 2 drill bits, and 3 saw blades. These accessories can meet various needs such as engraving, carving, sanding, polishing, etching, planing, grinding, drilling, and cutting. D. Start Your Engraving Art Journey Immediately: These portable and compact etching pens are easy to carry around, allowing you to enjoy making handmade jewelry. They can be used on materials such as metal, glass, ceramics, leather, wood, jewelry, stones, or statues.